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Scientists further refine how quickly the universe is expanding



 Scientists further refine how the universe is expanding
The team's analysis paves the way for better measurements in the future using telescopes from the Cherenkov telescope array. Credit: Photo courtesy of Daniel López / IAC
            

Wielding state-of-the-art technologies and techniques, a team of Clemson University astrophysicists has added a novel approach to quantifying one of the most fundamental laws of the universe.
                                               

The astrophysical journal Clemson scientists Marco Ajello, Abhishek Desai, Lea Marcotulli, and Dieter Hartmann have published a paper published on Friday, Nov. 8, in

"Cosmology is about understanding the evolution of our universe-how it evolves in the past, what it's doing now and what will happening in the future, "said Ajello, an associate professor in the College of Science's department of physics and astronomy. "Our knowledge on a number of parameters-including the Hubble Constant-that we strive to measure as-is-as-possible." In this paper, our team analyzed and ground-based telescopes to come up with one of the newest

The concept of an expanding universe was advanced by the American astronomer Edwin Hubble (1

889-1953), who is the name of the Hubble Space Telescope. In the early 20th century, Hubble became one of the first astronomers to deduce that the universe was composed of multiple galaxies.

Hubble originally estimated the expansion rate to be 500 kilometers per second per megaparsec, with a megaparsec being equivalent to about 3.26 million light years. Hubble is a galaxy two megaparsecs away from our galaxy what receding twice as fast as a galaxy only one megaparsec away. This estimate became known as the Hubble Constant, which proved to be the first time that the universe was expanding. Astronomers have been recalibrating it with mixed results-ever since.

Hubble's original calculations-slowing the expansion rate to 50 and 100 kilometers per second per megaparsec. And in the past decade, ultra-sophisticated instruments, such as the Planck satellite, have been subjected to the precision of Hubble's original measurements in a relatively dramatic fashion.

In a paper titled "A New Measurement of the Hubble Constant and Matter of Content Universe using Extragalactic Background Light-Gamma Ray Attenuation, "the collaborative team compared the latest gamma-ray attenuation data from the Fermi Gamma-ray Space Telescope and Imaging Atmospheric Cherenkov Telescopes to devise their estimates from extragalactic background light models. 67.5 kilometers per second megaparsec.

Gamma rays are the most energetic form of light. Extragalactic background light (EBL) is a cosmic fog of the ultraviolet, visible and infrared light emitted by stars in their vicinity.

 Clemson scientists continue to refine themselves as the universe is expanding
Clemson scientists Marco Ajello, Abhishek Desai, Lea Marcotulli and Dieter Hartmann have collaborated with six other scientists around the world to find a new measurement of the Hubble Constant. Credit: Jim Melvin / College of Science
            

"The astronomical community is investing a great deal of money and resources in all things different, including the Hubble Constant," said Dieter Hartmann, a professor in physics and astronomy. "Our understanding of the fundamental constants has become the universe of the future."

A common analogy of the expansion of the universe is a balloon dotted with spots, with each spot representing a galaxy.

"Some theorize that the balloon wants to expand to a particular point in time and then re-collapse," said Desai, a graduate research assistant in the department of physics and astronomy. But this is nothing more than an observable light. If this happens, it wants to be trillions of years from now. "

Matter – the stars, the planets, even us-is just a small fraction of the universe's overall composition, "Ajello explained. "The big majority of the universe is made of dark energy and dark matter." Dark energy is the dominant force at the local level, which is the more powerful force at the time of the collision. "

Alberto Dominguez of the Complutense University of Madrid; Radek Wojtak of the University of Copenhagen; Justin Finke of the Naval Research Laboratory in Washington, D.C .; Kari Helgason of the University of Iceland; Francisco Prada of the Institute of Astrofisica de Andalucia; and Vaidehi Paliya, a former postdoctoral researcher in Ajello's group at Clemson who is now at Deutsches Elektronen-Synchrotron in Zeuthen, Germany.

"It's remarkable that we are using gamma rays to study cosmology who is a former postdoctoral researcher in Ajello's group, said Dominguez. "Our results show the maturity reached in the last decade by the Cherenkov Telescope Array, which is still in development and will be the most ambitious array of ground-based, high-energy telescopes ever. "

Many of the same techniques used in the current paper correlate to previous work conducted by Ajello and his counterparts.

Science Ajello and his team were all to the starlight ever in the history of the universe.

"What we know is that gamma" ray photons from extragalactic sources in the universe towards Earth, where they can be absorbed by interacting with the photons from starlight, "Ajello said. If the expansion is low, they travel a long distance The Hubble Constant: "What we did and what it did was the expansion rate of the universe."
                                                                                                                        


How fast is the universe expanding? The mystery endures


More information:
Astrophysical Journal (2019). iopscience.iop.org/article/10. … 847 / 1538-4357 / ab4a0e

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Clemson University




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                                                 Scientists further refine how the universe is expanding (2019, November 8)
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